It is known that, in the dental domain, in order to ensure the perennity of the dental substance of a tooth, metal posts are called upon, which are screwed or sealed therein. Such metal posts present a certain number of drawbacks, which are principally associated with the great difference which exists between the mechanical characteristics of these posts and those of the dentine in which they are disposed.
In order to avoid such drawbacks, it has been proposed to employ posts made of composite material, constituted in particular by a matrix of bio-compatible resin, and particularly an epoxy resin, in which carbon or glass fibers are embedded.
In certain embodiments, the fibers are longitudinal fibers which extend over the whole length of the post and which are under equal tension therein. The posts thus constituted, by reason of their mechanical characteristics close to those of the dentine, considerably reduce the drawbacks set forth hereinabove.
However, such posts present the drawback of being transparent to X-rays, so that their positioning is particularly difficult to establish with the aid of the conventional apparatus available to practitioners.
These posts are usually manufactured by pultrusion, i.e. by a process of extrusion in which both the fibers, particularly the carbon or glass fibers, and a resin matrix are passed in the same die at the same time, the fibers being, all along the operation, maintained under tension. This operation of pultrusion is sometimes difficult to carry out by reason of the problems of obturation of the die of the extruder which occur during operation.
In the prior state of the art, products, or charges, are known, which are added to the dental reconstitution pastes, in order to give them a certain opacity to X-rays. U.S. Pat. No. 4,503,169 thus proposes to that end to include zirconium, oxides in dental reconstitution pastes.
Patent GB-A-2 028 855 also discloses a settable composition exempt of mercury based on a carboxylic polyacid and which contains, inter alia, filling elements which may possibly comprise fibrous elements which may be coated with metal oxides capable of reacting with the carboxylic polyacid in order to promote bond with the matrix.